XDH and obesity due to melanocortin 4 receptor deficiency: NaW, a xanthine oxidase inhibitor, has shown good diabetes and obesity treatment effects in different type 1 and type 2 diabetic animal models (Amigó-Correig et al. 2011; Nocito et al. 2012; Muñoz et al. 2001), and relevant clinical trials have been conducted (Hanzu et al. 2010).